In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of the common general knowledge or known to be relevant to an attempt to solve a problem with which this specification is concerned.
While the present invention will be described with particular reference to the disorder known as ‘heel spur’ the invention is not so limited but relates more generally to disorders or inflammation of the plantar fascia.
The plantar fascia (also known as the plantar aponeurosis) is a thick fibrous material that covers the soft tissue on the sole of the foot, providing static support for the medial longitudinal arch of the foot. The plantar fascia originates at the heel (specifically, at the medial tuberosity of the calcaneus), spreads out over the sole of the foot and terminates in the ligaments near the teratarsal heads in the forefoot. In use it helps to restrain motion within the joints of the ankle and forefoot.
The plantar fascia can become inflamed as a result of stress caused by overuse or as a result of a condition such as heel spur. Heel spurs typically develop as an abnormal growth in the front and bottom of the heel bone due to calcium deposits that form when the plantar fascia pulls away from the heel. Initially, sufferers commonly experience a dull intermittent pain in the heel which may develop into a sharp persistent pain. But it is not the spur that causes pain. The pain is caused by inflammation of the plantar fascia (known as plantar fasciitis). The classic sign of plantar fasciitis is heel pain with the first few steps in the morning. The pain is usually in the front and bottom of the heel, but it can be over any portion of the bottom of the foot where the plantar fascia is located. The pain varies in intensity from person to person and it can last a few months, become permanent, or come and go. Striking of the heel on the ground can exacerbate the condition, but is not a cause of the inflammation.
Causes of heel spur and subsequent inflammation of the plantar fascia include inadequate flexibility in the calf muscles, lack of arch support or sole cushioning in footwear, footwear that has inflexible soles, overweight, injury, sudden increase in physical activity, and spending too much time on the feet. Other causes of inflammation of the plantar fascia include arthritis, heel bone damage (“stress fracture”), loss of natural tissue for cushioning under the heel (“fat pad atrophy”) and tarsal tunnel syndrome.
The key to proper treatment of plantar fasciitis is determination of what is causing the excessive stretching of the plantar fascia. However in many cases, finding a specific cause is difficult. Typically, plantar fasciitis is treated with the use of a mixture of approaches as appropriate to the sufferer. These include losing weight, the use of orthotics, increasing cushioning in the sole of shoes, resting the foot, applying supporting tape and wearing of night splints. Application of ice often helps to reduce pain although many sufferers find it necessary to use analgesics such as ibuprofen cream that can be applied directly to painful areas. In more severe cases injections of painkillers may be used. Stretching the calf muscles using exercises that do not re-injure the fascia is a cure for many people. Typically these exercises are performed 3 times a day and especially before getting out of bed in the morning. Surgery may be necessary in extreme cases of plantar fasciitis.
Orthotic based treatment for plantar fasciitis include elevating the heel with the use of a heel cradle or heel cup. Heel cradles and heel cups provide extra comfort and cushion to the heel, and reduce the amount of shock and shear forces experienced from everyday activities. When the cause of plantar fasciitis is over-pronation (flat feet), an orthotic with rearfoot posting and longitudinal arch support is an effective device to reduce the over-pronation, and allow the condition to heal.
Many different devices have been developed to treat plantar fasciitis, particularly plantar fasciitis caused by heel spur. One such device for treatment of plantar fascia is described in U.S. Pat. No. 5,399,155 (Strassburg et al) and consists of an over the calf sock having a reinforced adjustable support strap attached around the upper portion of the sock with a “D” ring attached to the front (shin) side. A reinforced inelastic adjustable strap is attached to the toe of the sock, with a hook and loop assembly attached for closure. When this strap is passed through the “D” ring and secured by means of the hook and loop assembly, the plantar fascia can be maintained in the desired position. One of the disadvantages of this type of device, and many other orthotic devices, is that they hold the foot quite rigid so the wearer cannot walk. The device of U.S. Pat. No. 5,399,155 has an inelastic support strap hindering the normal action of the foot and ankle during walking hence use of the device is limited to times when the wearer is asleep or resting. Furthermore, solely treating heel spur by holding the plantar fascia in a neutral position and preventing movement or exercise is unlikely to cure heel spur.
Accordingly there is a need for a device having wider applicability, which can be used when the wearer is mobile as well as when they are sleeping or resting.